1. Field of the Invention
This invention relates generally to paper folding apparatus of the type employing interacting rotating cylinders and specifically to a guide shoe for guiding the paper from one cylinder to the other.
2. Description of the Related Art Including Information Disclosure Under 37 CFR 1.97-1.99
Referring to FIG. 1, a known folding apparatus, or folder, 10 is shown which employs a known guide shoe assembly 12 for guiding a ribbon of paper 14 from a folding cylinder 16 mounted for clockwise rotation in the direction of arrow 18 to a jaw cylinder 20 mounted for counterclockwise rotation in the direction of arrow 22 around a center axis 24.
The ribbon 14 first passes between a cutting cylinder 26 mounted for counterclockwise rotation in the direction of arrow 28 and the folding cylinder 16. A pair of cutting knives 30 on opposite sides of the cutting cylinder 16 cuts the ribbon 14 against a plurality of cutting rubbers 32 equally spaced around the folding cylinder 16.
The cut product 14' which extends between each pair of adjacent cutting rubbers is then carried by the folding cylinder 16 past a cylindrical guide shoe 34 to a folding station 36 at the juncture, or nib, between the folding cylinder 16 and the jaw cylinder 20. A plurality of tucker blade mechanisms 38 are located midway between each of the adjacent pairs of cutting rubbers 32. Those tucker blade mechanisms 38 successively align opposite a plurality of associated movable jaw assemblies 40 at the nib when the folding cylinder 16 and jaw cylinder are rotated during operation of the folder 10. When alignment occurs, the tucker blade mechanism 38 tucks in the middle of the cut product into an elongate slot 40' of the aligned movable jaw assembly 40 which produces an elongate crease therein and holds the cut product 14' as the product 14' is rotated away from the nib. The cut product 14' is then held at the middle crease, or fold, with the free edges trailing as the product 14' is carried to a delivery fly 42 by continued rotation of the jaw cylinder 20. When it reaches the fly 42, a jaw cylinder stripper shoe 44 removes the product 14' from the jaw cylinder. The folded and cut product is then received between an adjacent pair of arms of the delivery fly 42 and conveyed thereby to stripper wheels 46. The stripper wheels 46 remove the product 14' and lay it on a delivery belt 48. The folded product 14' is then delivered by the belt 48 in a shingled stream with the folded edge forward.
When the folded product is being transferred from the folding cylinder 16 to the jaw cylinder 20, the free ends of the folded product 14' rapidly change direction as the crease held by jaw cylinder 20 is rotated upward and to the left while the free ends are still being rotated generally to the right. This causes the corners of the folded product opposite the crease to fold over and forms dog-ears in a fold out area 50. If these dog-ears are permitted to remain, they tend to cause problems in the product flow downstream of the delivery belt 48.
Accordingly, it is known to provide a guide shoe assembly 52 over the jaw cylinder 20 to reduce the formation of dog-ears. The known guide shoe 52 has a guide section 54 which is concentric with the jaw cylinder 20 and which is placed very close to the cylindrical surface of the jaw cylinder 20 by a gap on the order of 250 mils. Another guide section is defined by a curved arm 56 pivotally mounted at the inlet end of the cylindrical section 54. As seen, the angular extent 53 of the entire guide shoe assembly 52 is substantially less than the ninety degree section between the four jaw assemblies 40 and the angular extent of the cylindrical section is less than half of the total length of the guide shoes 52. Accordingly, the paper product 14' is forced to rapidly and abruptly conform to the cylindrical shape of the jaw cylinder 20. This is done based on the belief that the dog-ears can be removed by abruptly and rapidly forcing the paper into conformance with the surface of the jaw cylinder 20. However, this known guide shoe assembly 52 is often ineffective in reducing the dog-ear problem and, in fact, is believed to aggravate the problem.